Question - looking at the code quickly, I see stuff about MWCC and Metrowerks object file format - is your tool chain in some way generating Metwowerks compatible object files? BeOS PowerPC uses the same compiler so you got me excited!
I reverse-engineered enough of the .o header format so that MacRelix's ar and ld could retrieve architecture and runtime information from a static library instead of making the caller provide it via a switch.
Separately, I've been writing post-linkers that patch or rewrite the Metrowerks-provided startup code in 68K code resources. The next step on this path might be writing my own compatible linker.